The present invention relates to a printed circuit board mounted connector used to connect electronic devices such as personal computers through cables and, more particularly, to a shield structure of the connector.
A typical conventional printed circuit board mounted connector (to be referred to as a socket connector hereinafter) of this type is disclosed in Japanese Utility Model Laid-Open No. 61-201284. This socket connector will be described with reference to FIGS. 4A to 8.
FIGS. 4A and 4B show the conventional socket connector, FIG. 5 shows an annular shield used in this socket connector, FIG. 6 shows a shield plate used in the socket connector, FIG. 7 shows a state of use of the socket connector, and FIG. 8 shows a plug cable connected to the conventional socket connector. Referring to FIGS. 4A to 8, reference numeral 1 denotes a conventional socket connector. The socket connector 1 comprises an insulating body 3 incorporating female terminals 2, and an annular shield 4 and a shield plate 5, latter two of which are mounted on the insulating body 3. The female terminals 2 are respectively inserted and fixed in female terminal accommodating holes 3a formed in the insulating body 3. One end of each female terminal 2 extends below the insulating body 3. An annular recessed groove 3b open to the front surface is formed at the connecting port of the insulating body 3. The annular shield 4 is mounted in the annular recessed groove 3b. The annular shield 4 consists of a conductive material and has almost a cylindrical shape as a whole, as shown in FIG. 5. A one-end portion of the annular shield 4 at a position corresponding to the connecting port is tapered so that the diameter is increased toward the distal end. A shield terminal 4a is formed integrally with the other-end portion of the annular shield 4 to extend below the insulating body 3. The shield plate 5 consists of a conductive material. As shown in FIG. 6, the shield plate 6 has an inverted-U shaped member which covers both side surfaces and the upper surface of the insulating body 3. A flange 5b connected to a shield panel (to be described later) and having a screw hole 5a is formed integrally with the shield plate 5 at a position corresponding to the upper surface of the insulating body 3. Shield terminals 5c are formed integrally with lower end portions of the shield plate 5 at positions corresponding to the side surfaces of the insulating body 3. The shield terminals 5c extend below the insulating body 3. Reference numeral 6 denotes a printed circuit board on which electronic components (not shown) are to be mounted. The extended end portions of the female terminals 2 and the shield terminals 4a and 5c of the socket connector 1 are connected to the printed circuit board, so that the socket connector 1 is mounted on the printed circuit board 6. The printed circuit board 6 is arranged so that the shield terminal 4a of the annular shield 4 is electrically connected to the shield terminals 5c of the shield plate 5 through the printed circuit board 6. More specifically, when the socket connector 1 is mounted on the printed circuit board 6, the annular shield 4 and the shield plate 5 are electrically connected through the printed circuit board 6. Reference numeral 7 denotes a shield panel serving as a ground plate constituting the frame of the electronic device. The shield panel 7 stands upright on the printed circuit board 6 at its connecting port which connects the socket connector 1. A plug cable insertion opening 7a (to be described in detail later) is formed in the socket connector 1 at a position corresponding to the connecting port. Reference numeral 8 denotes a plug cable connected to the socket connector 1. Male terminals 8a to be connected to the female terminals 2 of the socket connector 1, and an annular shield 8b which shields a cable (not shown) and is connected to the annular shield 4 of the socket connector 1 are formed at the fitting portion of the plug cable 8, as shown in FIG. 8. It should be noted that the annular shield 8b has a size enough to fit the annular shield 8b into the opening of the annular shield 4.
In order to mount the conventional socket connector having the above structure, the socket connector 1 is mounted on the printed circuit board 6, and the flange 5b of the shield plate 5 is fixed by a screw 9 to the shield panel serving as the frame of the electronic device. At this time, the shield plate 5 of the socket connector 1 is electrically connected to the shield panel 7.
In order to connect the plug cable 8 to the socket connector 1 attached to the electronic device described above, the annular shield 8b of the plug cable 8 is inserted into the opening 7a of the shield panel 7 and then the annular recessed groove 3b of the insulating body 3. When the annular shield 8b is fitted in the annular recessed groove 3b of the insulating body 3, this annular shield 8b is brought into contact with the annular shield 4 of the socket connector 1 and is electrically connected thereto. At the same time, the male terminals 8a are connected to the corresponding female terminals 2.
When the plug cable 8 is connected to the socket connector 1 as described above, the annular shield 8b of the plug cable 8 is connected to the shield panel 7 through the annular shield 4 of the socket connector 1, the printed circuit board 6, and the shield plate 5 of the socket connector 1 in the order named, thereby providing a shield implementation of the plug cable 8.
In the conventional socket connector 1 having the above structure, when the shield of the plug cable 8 is to be connected to the shield of the electronic device, the shield of the plug cable 8 is short-circuited to the shield plate 5 of the socket connector 1 through the annular shield 4 of the socket connector 1 and the printed circuit board 6 and is connected to the shield panel 7 through the flange 5a of the shield plate 5 and its screw portion. In this manner, the shield of the plug cable is connected through a lot of connecting points. For this reason, shield impedances vary, and a stable shield effect cannot be obtained.